On Mon, Aug 14, 2017 at 8:40 PM, Tom Lane <t...@sss.pgh.pa.us> wrote:

> It would be possible to have orphaned non-temp tables if you'd suffered
> a crash during the transaction that created those tables.  Ordinarily
> a newly-created table file wouldn't be that large, but if your workflow
> created tables and shoved boatloads of data into them in the same
> transaction, it's not so hard to see this becoming an issue.

I think the working theory is that these were very like a number of very
large (multi-hundred-GB materialised views).

> The core problem with zapping non-temp table files is that you can't
> do that unless you're sure you have consistent, up-to-date pg_class
> data that nobody else is busy adding to.  It's hard to see an external
> application being able to do that safely.  You certainly can't do it
> at the point in the postmaster startup cycle where we currently do
> the other things --- for those, we rely only on filesystem naming
> conventions to identify what to zap.

Yeah that occurred to me. At this point I would settle for something I
could run with Postgres in single user mode.  Although that is very far
from ideal.  So what I wonder is if at least a short-term solution might be
a utility that starts Postgres in single user mode and we insist that
PostgreSQL is otherwise not running before the run.

I am certainly not feeling qualified at present for more advanced solutions
but that I might be able to do.

>                         regards, tom lane

Best Regards,
Chris Travers
Database Administrator

Tel: +49 162 9037 210 | Skype: einhverfr | www.adjust.com
Saarbrücker Straße 37a, 10405 Berlin

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